I have posted twice in the past week about noise from my rear differential on my 99 f150 4x4. I think I have it narrowed down to the clutch pack and I am going to have to drive about 30-40 miles to the shop where its going to be fixed (quoted around $600 over the phone). My question is what kind of damage can be done internally or what is the worst thing that could possibly happen to the diff during my drive, if it needs to be towed maybe I should go that route. What are anyones thoughts?

 

Your clutch packs could just be a little glassy I tore mine down took the pigs head to a shop and they buffed the clutches for me good as new!

 

You have made an incorrect diagnostic.

When the clutch packs in the diff wear out, they simply deplete. No harm done whatsoever. It will act like a traditional axle and you can drive until the rest of the vehicle breaks.

However you will not have the awsome trac lock anymore, so only one wheel will spin in the rain or snow.

It costs about $80 to 100 for the clutches, $20 for the s-spring. There is no way a job should approach that cost. Maybe $200 labor for a good shop.

You need to look elsewhere for your noise. You could have s snapped spider gear in which it is not drivable. Or nothing is wrong other than a a hanging e-brake, or a rusted backing plate dragging on the rotor. One you can find out, and you need to do this before letting a shop charge you than kind of money.

 

This is my problem....a few months ago I took it to a local shop for vibration from the rear end, it needed u joints and I was told the pinion bearing was going out, I took it to a specialty shop where I was told the bearing was fine and off I went.
Now I have a noise from the rear end that seems to go along with the speed of the drive shaft, I have checked the fluid and it is full, I have checked for play at the yoke there is none, the noise is constant during accel and decel.I have even jacked it up and put it in gear and didnt hear anything abnormal. When I have the front wheels turned and I take off there is a little vibration, also after jacking it up today I noticed that the wheels are hard to turn when it is in neutral and no the braked arent sticking. I called the same specialty shop and explained to him the new problem and he told me it sounded like a clutch pack, when asked about the cost he said it shouldnt exceed $600. This is all being done sight unseen and diagnosing it over the phone, not looking up the parts price, assuming it is the clutch pack.

 

Clutch packs don't have that effect, period!
Here is what your missing in the thinking.
The clutch paks are alternate discs of steel and discs with friction material.
They are forced togather by the S spring to effect a 'limited slip' function.
If they wear out, they just slip most of the time around turns or when traction on one wheel occurs and do no other harm.
The only time they can cause any chatter is if they 'WORK TO GOOD" and cause one wheel to 'sprag' going around a turn.
If that becomes the case, the addition of special additive to the rear fluid to make the clutcd slip more, is the answer.
Many people think additive works the oppisite, but it does not.
To test the limited slip function, jack up one side with trans in neutral and front wheels block for safety and use a tool with enough leverage to turn the wheel and see how much force it takes to make the clutch pak on that side slip. Using a torque wrench typically will show a good pak takes 40 feet pound or something greater before the cluch lets go.
This is the same action that would ocurr if one wheel had traction and one did not under power from the driveshaft.
BTW, the S spring is a tough item to get back in once you remove it.
I made a special tool that makes it a very easy job. The PU springs are usually heavier than in a 8.8 car rear.
The Drag boys often use the PU spring in Mustangs and other cars as well as repacking the stackup to get even more lockup using slicks.
Good luck.

 

Ok, with the information that I have provided what would you assume the problem to be and what would you do about it? Of course this is all for fun because we can assume all we want but until someone actually removes the cover and diagnoses it correctly we will never no. Once I get the diagnosis/price I will post it here.

 

i missed your first threads, do you have an 8.8 or a 9.75 rg? just by what has been said here i would talk to the people from the first shop that said the pinion bearing.

 

Last Friday my truck was finished and this is what was wrong with it...clutch pack failed/replaced....carrier bearing races pitted....replaced those along with all the other bearings...total cost with tax $508...what I dont understand is why I had this issue with only 131k miles...anyway the job is done, hopefully this helps someone else in the future.

 

break in wear leaves some kinds of crud in the gear lube. I like to drain that out after 20k miles. Some small crud got into the bearings and a few nicks developed in the races. You eventually end up with a "whine". Someday it could lead to a failure, but was not failed now.. Some "crud" also can come from the friction discs on the clutch. THe clutch was not your problem, but not a bad idea to replace and adjust. Should be good as new.

 

For what it is worth I had a 9 inch rear end on a 1980 that had the stuck on magnet come loose and and was ground up and wrecked the carrier bearings at only 85k miles so, crap happens. The chunks were a golden color.